The invention disclosed and claimed herein generally pertains to the field of diving safety devices of the type which enable a diver to easily and continually keep track of his maximum depth of submergence. More particularly, the invention pertains to the field of devices of the above type which comprise solid state electronic components, to eliminate the need for periodic calibration. Even more particularly, the invention pertains to the field of devices of the above type which have the capability of warning the diver by means of an audio alarm that he has reached a critical maximum depth of submergence.
It is well known that diver safety is affected by two critical parameters, i.e., the length of time a diver has been submerged, or bottom time, and his maximum depth. According to standard practice of the U.S. Navy, a diver's maximum depth is taken to be the lowest level to which he has descended at any point during a dive, regardless of the amount of time he remains at such level.
The above two parameters are critical because, taken together, they determine whether or not a diver will have to make decompression stops at the conclusion of his dive, and if so, the respective levels and times of the decompression stops. Failure to adhere to a decompression schedule which is demanded by the combination of two particular values of bottom time and maximum depth can result in severe injury or death, due to the phenomenon known as "the bends". At the same time, a diver using SCUBA equipment (self contained underwater breathing apparatus) is severely constrained in the amount of time he may spend underwater, since his air supply is limited. Consequently, it may be of the utmost importance for a diver to keep track of his maximum depth, to avoid getting into a situation where the combination of his maximum depth and bottom time require him to make decompression stops for which he does not have sufficient air.
In the past, various types of pressure gauges and bathometers have been provided which enable a diver to see his current depth, at any point during a dive. Since a depth gauge provides only current depth information, a diver must continually check his depth gauge, and must somehow be able to record or remember the maximum depth shown. Because a diver usually is preoccupied by underwater tasks, continuous monitoring of a depth gauge may be virtually impossible. It is often difficult or impossible to record or to recall maximum observed depth, despite the critical importance of doing so.
In a patent to Jennings, U.S. Pat. No. 4,005,282, issued Jan. 25, 1977, a miniature computer is provided, which is programmed with depth, time and decompression relationships to provide a diver with information pertaining to a safe ascent. The Jennings system was developed as part of the continuing effort of the U.S. Navy to improve diver safety, and is considered to be a major achievement. However, since it is a computer device, it may be somewhat complicated, and comparatively expensive. Also, when the combination of a diver's depth and bottom time become such that the diver is placed in a potentially hazardous condition, the diver is alerted only by means of a small flashing light which might be completely missed by a working diver.
Thus, there is a continuing need in the state of the art for enhancing the safety of a diver by enabling him to rapidly determine, at any point during a dive and with minimal distraction, his maximum depth of submergence up to such point. Such a device should continually indicate a diver's maximum depth, eliminate the need for continuous monitoring, to have a maximum depth memory and provide an audio warning. Inexpensive solid state electronic components, eliminating the need for periodic calibration should be employed, and be arranged in either a wrist mounted mode or a mode mountable on a diver propelled vehicle (DPV).